/*
 * Copyright 2017 data Artisans GmbH Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License. You may obtain a copy of the
 * License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed
 * to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 */

package com.dataartisans.flinktraining.solutions.datastream_java.process;

import com.dataartisans.flinktraining.exercises.datastream_java.datatypes.TaxiFare;
import com.dataartisans.flinktraining.exercises.datastream_java.datatypes.TaxiRide;
import com.dataartisans.flinktraining.exercises.datastream_java.sources.CheckpointedTaxiFareSource;
import com.dataartisans.flinktraining.exercises.datastream_java.sources.CheckpointedTaxiRideSource;
import com.dataartisans.flinktraining.exercises.datastream_java.utils.ExerciseBase;
import org.apache.flink.api.common.state.ValueState;
import org.apache.flink.api.common.state.ValueStateDescriptor;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.api.java.utils.ParameterTool;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.streaming.api.TimeCharacteristic;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.co.CoProcessFunction;
import org.apache.flink.util.Collector;
import org.apache.flink.util.OutputTag;

/**
 * Java reference implementation for the "Expiring State" exercise of the Flink training
 * (http://training.ververica.com).
 *
 * The goal for this exercise is to enrich TaxiRides with fare information.
 *
 * Parameters: -rides path-to-input-file -fares path-to-input-file
 *
 */
public class ExpiringStateSolution extends ExerciseBase {
    static final OutputTag<TaxiRide> unmatchedRides = new OutputTag<TaxiRide>("unmatchedRides") {
    };
    static final OutputTag<TaxiFare> unmatchedFares = new OutputTag<TaxiFare>("unmatchedFares") {
    };

    public static void main(String[] args) throws Exception {

        ParameterTool params = ParameterTool.fromArgs(args);
        final String ridesFile = params.get("rides", ExerciseBase.pathToRideData);
        final String faresFile = params.get("fares", ExerciseBase.pathToFareData);

        final int servingSpeedFactor = 600; 	// 10 minutes worth of events are served every
                                            	// second

        // set up streaming execution environment
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        env.setStreamTimeCharacteristic(TimeCharacteristic.EventTime);
        env.setParallelism(ExerciseBase.parallelism);

        DataStream<TaxiRide> rides = env
                .addSource(rideSourceOrTest(
                        new CheckpointedTaxiRideSource(ridesFile, servingSpeedFactor)))
                .filter((TaxiRide ride) -> (ride.isStart && (ride.rideId % 1000 != 0)))
                .keyBy("rideId");

        DataStream<TaxiFare> fares = env
                .addSource(fareSourceOrTest(
                        new CheckpointedTaxiFareSource(faresFile, servingSpeedFactor)))
                .keyBy("rideId");

        SingleOutputStreamOperator processed = rides.connect(fares)
                .process(new EnrichmentFunction());

        printOrTest(processed.getSideOutput(unmatchedFares));

        env.execute("ExpiringStateSolution (java)");
    }

    public static class EnrichmentFunction
            extends CoProcessFunction<TaxiRide, TaxiFare, Tuple2<TaxiRide, TaxiFare>> {
        // keyed, managed state
        private ValueState<TaxiRide> rideState;
        private ValueState<TaxiFare> fareState;

        @Override
        public void open(Configuration config) {
            rideState = getRuntimeContext()
                    .getState(new ValueStateDescriptor<>("saved ride", TaxiRide.class));
            fareState = getRuntimeContext()
                    .getState(new ValueStateDescriptor<>("saved fare", TaxiFare.class));
        }

        @Override
        public void processElement1(TaxiRide ride, Context context,
                Collector<Tuple2<TaxiRide, TaxiFare>> out) throws Exception {
            TaxiFare fare = fareState.value();
            if (fare != null) {
                fareState.clear();
                out.collect(new Tuple2(ride, fare));
            } else {
                rideState.update(ride);
                // as soon as the watermark arrives, we can stop waiting for the corresponding fare
                context.timerService().registerEventTimeTimer(ride.getEventTime());
            }
        }

        @Override
        public void processElement2(TaxiFare fare, Context context,
                Collector<Tuple2<TaxiRide, TaxiFare>> out) throws Exception {
            TaxiRide ride = rideState.value();
            if (ride != null) {
                rideState.clear();
                out.collect(new Tuple2(ride, fare));
            } else {
                fareState.update(fare);
                // as soon as the watermark arrives, we can stop waiting for the corresponding ride
                context.timerService().registerEventTimeTimer(fare.getEventTime());
            }
        }

        @Override
        public void onTimer(long timestamp, OnTimerContext ctx,
                Collector<Tuple2<TaxiRide, TaxiFare>> out) throws Exception {
            if (fareState.value() != null) {
                ctx.output(unmatchedFares, fareState.value());
                fareState.clear();
            }
            if (rideState.value() != null) {
                ctx.output(unmatchedRides, rideState.value());
                rideState.clear();
            }
        }
    }
}
